Patients with hepatobiliary diseases (e.g., diseases of the liver, gallbladder and biliary tract), conditions of the pancreas (e.g., chronic pancreatitis, pancreatic cancer), and visceral artery insufficiency can all suffer from chronic and/or intractable pain. Such pain associated with these conditions, for example, can be both debilitating and difficult to treat. Typically, analgesics and/or narcotics are used to manage the patient's pain; however, conventional pain-management medications (e.g., opiates) are often ineffective or only partially effective and can cause undesirable side effects and dependency. Conventional non-pharmacological treatments for the treatment of conditions of the pancreas, for example, can include locally injecting anesthetic drugs or nerve-destroying agents (e.g., alcohol) to reduce nerve signaling through the celiac ganglia and/or celiac plexus. This procedure, known as a “celiac plexus block,” can be effective in some cases, but its effectiveness tends to diminish over time. For example, the procedure must typically be repeated every three to four months for sustained pain management. Furthermore, executing a conventional celiac plexus block involves inserting a needle through the gastrointestinal, intraabdominal and/or retroperitoneal anatomy to a position proximate the celiac plexus. This manner of accessing the celiac plexus can be imprecise and can have a variety of serious potential complications, include retroperitoneal hemorrhage, spinal-cord puncture, and paraplegia. Accordingly, there is a need for alternative treatments.
Chronic pain can also be associated with both male and female reproductive/genital organs. For example, orchialgia is a condition characterized by long term testicular pain that often has no known etiology but can in some cases be caused by injury, infection, surgery, cancer or testicular torsion and can be a possible complication after vasectomy. Vulvodynia is a condition characterized by chronic pain affecting the vulvar area and often occurs without an identifiable cause or visible pathology. Both orchialgia and vulvodynia are treated, for example, with anti-inflammatory medications or other pain medications, antidepressants (e.g., nortriptyline, amitriptyline), and anti-anxiety drugs; however, these are not always effective and can have undesirable side effects. Intractable cases of orchialgia can be treated with microsurgical denervation of the spermatic cord; however, the procedure has several potential complications (e.g., testicular atrophy, hydrocele, hypoesthesia of the scrotum, penile shaft, inguinal or medial thigh skin, and persistent testicular pain). Intractable cases of vulvodynia can be treated with injection or surgical destruction of the pudendal nerve; however, the procedure has several potential complications (e.g., permanent vulva numbness, continued vulvodynia pain, etc.). Accordingly, there is a need for alternative treatments.
Pain signals travel along various neural pathways through the body, including the sympathetic nervous system (SNS). The SNS is a primarily involuntary bodily control system typically associated with stress responses. Fibers of the SNS extend through tissue in almost every organ system of the human body. For example, some efferent SNS fibers extend from the brain, intertwine along the aorta, and branch out to various organs. Likewise, afferent nerve fibers traveling with SNS nerve fibers can transmit signals, including pain signals, from the organs (e.g., abdominal organs, reproductive/genital organs) to the brain.